1. Field of the Invention
The present invention relates to targets, more particularly to object simulators and to a method for effectively converting power contained in a heated airstream into specific infrared radiation in a controlled manner to bring about a desired effect. According to the invention, the infrared radiation is produced at various specified intensities and locations to generate a desired characteristic infrared signature. The infrared signature generated thereby is then used to simulate the infrared signature produced by objects that would be targets for an infrared tracking weapon, such as armored vehicles, support vehicles, and the like. Because of the method used to produce infrared radiation, this invention will improve the quality of infrared signatures produced by object simulators and reduce the size of the power supplies required to produce the infrared signatures.
2. Description of the Prior Art
It is known in the art to generate infrared specific signatures for decoys or target systems for heat-sensing weapons or devices. The infrared signature of a specific target object, such as a tank or personnel carrier for example, is known, and a target made to simulate the target object is constructed to produce a like infrared signature.
A variety of techniques have been used for this purpose. The techniques commonly used by the U.S. Army employ electricity and resistive heating as the power transfer medium. Electricity is produced by an electrical generator which is typically driven by a gasoline or diesel-fueled internal combustion engine. The electricity conducts through heating elements. As current conducts through the elements, heat is generated and released in the form of infrared radiation at specified locations, producing the desired infrared signature of an intended target object.
Another method of generating a desired infrared signature uses heated air as the power transfer medium. This method passes a heated airstream between two carefully located gas impermeable sheets to raise the surface temperature of the sheets, thereby producing the desired infrared signature of an intended target object.
A third method uses heat created by chemical reactions. One of these uses plastic bags containing isolated portions of calcium chloride and water. When the bag is struck, the calcium chloride and water mix together causing a heat producing chemical reaction. The result is that the temperature of the bags rises, thereby generating an infrared signature like that of the intended target object.
All three of these prior art methods of generating an infrared signature have significant disadvantages. For example, the electrical/resistive systems are heavy, and the signature they create is weak and easily affected by the wind. Furthermore, the fuel for the electrical generators is volatile, and the heating elements tend to fail when folded repeatedly. The heated air systems are also easily effected by the wind, and the power supplies for this type of system are large and heavy. Finally, the chemical approach only provides about two hours of operation. This is far below the operating time generally desired for most applications.